CHAP. II. HYBRID VEEBASCUMS. 79 



off, however often and severely the stem may be struck. 

 In this curious property the above-described hybrids 

 took after V. thapsus; for I observed, to my surprise, that 

 when I pulled off the flower-buds round the flowers 

 which I wished to mark with a thread, the slight jar 

 invariably caused the corollas to fall off. 



These hybrids are interesting under several points of 

 view. First, from the number found in various parts 

 of the same moderately-sized field. That they owed their 

 origin to insects flying from flower to flower, whilst col- 

 lecting pollen, there can be no doubt. Although in- 

 sects thus rob the flowers of a most precious substance, 

 yet they do great good; for, as I have elsewhere 

 shown,* the seedlings of V. thapsus raised from flowers 

 fertilised with pollen from another plant, are more 

 vigorous than those raised from self-fertilised flowers. 

 But in this particular instance the insects did great 

 harm, as they led to the production of utterly barren 

 plants. Secondly, these hybrids are remarkable from 

 differing much from one another in many of their 

 characters ; for hybrids of the first generation, if 

 raised from uncultivated plants, are generally uni- 

 form in character. That' these hybrids belonged to 

 the first generation we may safely conclude, from the 

 absolute sterility of all those observed by me in a state 

 of nature and of the one plant in my garden, excepting 

 when artificially and repeatedly fertilised with pure 

 pollen, and then the number of seeds produced was 

 extremely small. As these hybrids varied so much, an 

 almost perfectly graduated series of forms, connecting 

 together the two widely distinct parent-species, could 

 easily have been selected. This case, like that of 

 the common oxlip, shows that botanists ought to be 



1 The Effects of Cross and Self-fertilisation,' 187G, p. 89. 



